-If we are talking about regular SD cards, there is no internal wear leveling. It is up to the driver to do that.
-It take can take up to something like 40ms to write a single sector, as an entire block must be erased and re-written.For a given card, it is indeed specified. Cards have different speeds, but that that is available from the internal config data of the card and the mfg specs - which are published. The card indicated via status when it is done (of course only the driver is going to see that) -As for "low level formatting", huh? Unlike a hard drive, a sector is a sector. While writing a stand alone driver, I scrambled the data plenty of times, and reformatting with windows "format" never failed to work. You might be assuming it is like CF, which does emulate a hard drive. You should get the spec from the SD people for 1.1 and read (parts of) it. I think your issues are with the the OS/Driver and the way you are doing things. Used correctly, SD cards will work fine. Unless you have many files open, it should complete quickly. On Wed, Mar 25, 2009 at 7:06 AM, Erwin Authried <[email protected]> wrote: > Am Mittwoch, den 25.03.2009, 11:30 +0100 schrieb Michael Schnell: > > > My SD card is getting corrupted after issuing the reboot command and > > > de-powering the board. > > Are you sure it was unmount before shutting down the system ? > > > > BTW.: > > Even if you do unmount it you are not safe. An SD-Card (like all similar > > flash media) does an internal wear leveling. This can take an > > unspecified amount of time after any write request. If you de-power the > > SD-Card before this timespan is over it might be corrupted. Not only the > > newly written data might be corrupt but any data on the card. I ever > > read reports claiming that it can get so seriously corrupted that it > > could not be formatted any more and a low-level formatting with a > > special tool was necessary. > > > > -Michael > > Hi Michael, > > that sounds like SD cards cannot be used for anythiing serious. I'd like > to know if this applies to industrial SD cards as well. What is the > source of the information that you have? I'd really like to see that!! > > -Erwin > > > _______________________________________________ > uClinux-dev mailing list > [email protected] > http://mailman.uclinux.org/mailman/listinfo/uclinux-dev > This message was resent by [email protected] > To unsubscribe see: > http://mailman.uclinux.org/mailman/options/uclinux-dev >
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